The titular "Anna" was the code-name of the eight-year investigation of the serial murders committed by the "Vampire of Silesia". The investigation was code-named after the first known victim of Zdzislaw Marchwicki.
The project began as a documentary, but during an early stage of the production, a decision was made to adapt the true story as a film instead.
Most of the scenes depicting the crimes were filmed in the locations of the actual murders.
All photographs of the crime scenes, the victims, and the autopsies, viewed by the investigators during multiple scenes, are real photographs taken from the case files of the actual investigation of Zdzislaw Marchwicki's crime spree.